Training induced decrease in oxygen cost of cycling is accompanied by down-regulation of SERCA expression in human vastus lateralis muscle.
We have examined the effect of 5 week cycling endurance training program on the sarco(endo)plasmic reticulum Ca2+ ATPase isoforms (SERCA1 and 2) and myosin heavy chain (MyHC) in the vastus lateralis muscle as well as on the oxygen uptake to power output ratio (VO2/PO) during incremental cycling. Fifteen untrained men performed an incremental cycling exercise until exhaustion before and after moderate intensity training. Muscle biopsies were taken from vastus lateralis before and after training program. Training resulted in higher (P = 0.048) maximal oxygen uptake (VO(2max)) as well as in higher power output reached at VO(2max) (P = 0.0001). Moreover, lower (P = 0.02) VO2/PO ratio determined during incremental moderate intensity cycling (i.e. 30-120 W) as well as lower (P = 0.003) VO2/PO ratio reached at VO(2max) were observed after the training. A significant down regulation of SERCA2 protein (P = 0.03) and tendency (P = 0.055) to lower SERCA1 content accompanied by lower (P<10(-4)) plasma thyroid hormone concentration, with no changes (P = 0.67) in MyHC composition in vastus lateralis muscle were found after training. We have concluded that the increase in mechanical efficiency of cycling occurring during first weeks of endurance training is not related to changes in MyHC composition but it may be due to down-regulation of SERCA pumps.
Majerczak
J
J
Department of Physiology and Biochemistry, Faculty of Rehabilitation, University School of Physical Education, Krakow, Poland.
Karasinski
J
J
Zoladz
J A
JA
D015308:Anaerobic Threshold / Q000502:physiology; D001642:Bicycling / Q000502:physiology*; D015153:Blotting, Western; D015992:Body Mass Index; D015536:Down-Regulation; D004591:Electrophoresis, Polyacrylamide Gel; D005080:Exercise Test; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology*; D018995:Myosin Heavy Chains / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology*; D010807:Physical Endurance; D010809:Physical Fitness / Q000502:physiology*; D011659:Pulmonary Gas Exchange / Q000502:physiology; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000096:biosynthesis* / Q000235:genetics; D013963:Thyroid Hormones / Q000097:blood; D055815:Young Adult
D013963:Thyroid Hormones; D019344:Lactic Acid; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D018995:Myosin Heavy Chains; C506943:ATP2A1 protein, human; C506946:ATP2A2 protein, human